Laser-induced electron dynamics and surface modification in ruthenium thin films

Akhmetov, Fedor; Milov, Igor; Semin, Sergey; Formisano, Fabio; Medvedev, Nikita; Sturm, Jacobus Marinus; Zhakhovsky, V. V.; Makhotkin, Igor A.; Kimel, A. V.; Ackermann, Marcelo

doi:10.1016/j.vacuum.2023.112045

Cited by 7 publications

(3 citation statements)

References 43 publications

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“…In this case, no transmission of laser light was detectable, all of it being partially absorbed and partially reflected by the thick metal layer. The penetration depth for 800 nm light in ruthenium is approximately 15 nm . When illuminating the 150 nm thick ruthenium sample from the metal side, no light reaches the Ru/substrate interface.…”

Section: Resultsmentioning

confidence: 99%

“…The penetration depth for 800 nm light in ruthenium is approximately 15 nm. 24 When illuminating the 150 nm thick ruthenium sample from the metal side, no light reaches the Ru/substrate interface. In addition, the electron–phonon coupling constant in Ru is high, so that on the time scale of a few picoseconds, a negligible amount of electron energy reaches the Ru/substrate interface.…”

Section: Resultsmentioning

confidence: 99%

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Femtosecond Laser-Induced Emission of Coherent Terahertz Pulses from Ruthenium Thin Films

Cruciani,

van Vliet,

Troglia

et al. 2023

J. Phys. Chem. C

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We demonstrate emission of electromagnetic pulses with frequencies in the terahertz (THz) range from ruthenium thin films through a second-order nonlinear optical process. Ruthenium deposited on different substrates showed different THz emission properties. We provide evidence that for Ru on glass above a certain power threshold, laser-induced oxidation occurs, resulting in an increased slope of the linear dependence of the THz electric field amplitude on pump power. The THz electric field is mainly polarized parallel to the sample surface, pointing in the same direction everywhere. In contrast to Ru on glass, the electric field amplitude of the THz pulses emitted by Ru on sapphire and on CaF2 shows a simple single linear dependence on pump power, and it is polarized orthogonal to the sample surface. In this case, thermal oxidation in an oven enhances the emission and introduces an additional polarization component along the sample surface. This component also points in the same direction everywhere on the surface, similar to the as-deposited Ru on glass. Although the precise THz generation mechanism remains an open question, our results show a strong correlation between the emission strength and the degree of oxidation. Furthermore, the results highlight the importance of the interfaces, i.e., both the choice of the substrate and the chemical composition of the top surface in THz emission experiments. Knowledge of the state of the sample surface is therefore crucial for the interpretation of THz emission experiments from (nonmagnetic) metal surfaces.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Femtosecond Laser-Induced Emission of Coherent Terahertz Pulses from Ruthenium Thin Films

Cruciani,

van Vliet,

Troglia

et al. 2023

J. Phys. Chem. C

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“…Therefore, a proper technology is needed in order to Coatings 2023, 13,1947 2 of 13 prevent this damage. Surface modification technology can effectively strengthen and repair the parts, and improve the hardness and wear resistance, and extend the parts' service lives [7][8][9]. This is of great significance in industrial production and in the protection of human life and property safety.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Properties of Inconel 718 Coatings with Different Laser Powers on the Surface of 316L Stainless Steel Substrate

Liu,

Zhu,

et al. 2023

Coatings

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Laser cladding is a new method to prepare coatings with good quality. Laser power is one of the main factors affecting the quality of laser cladding coatings. An appropriate laser power helps obtain a high-performance laser cladding coating. In order to obtain coatings with good quality, an experiment with different laser powers was designed in this research. Three Inconel 718 coatings with different laser powers were prepared on the surface of a 316L stainless steel substrate. And the effect of different laser powers (1400, 1600, and 1800 W) on the microstructure, phases, and element distribution of coatings (L1–L3) was investigated by SEM, EDS, XRD, and a wear and friction tester. Meanwhile, the microhardness and friction and wear properties of different coatings were analyzed. The results show that the coatings’ phases were the same and composed of γ~(Fe, Ni) solid solution, Ni3Nb, (Nb0.03Ti0.97)Ni3, MCX (M = Cr, Nb, Mo), and so on. The background zones in the L1–L3 coatings were mainly the Fe and Ni elements. The irregular blocks in the coating were rich in Cr, Mo, and Nb, which formed the MCX (M = Cr, Nb, Mo) phase. When laser powers were 1400, 1600, and 1800 W, the average microhardness of the three coatings was 685.6, 604.6, and 551.9 HV0.2, respectively. The L1 coating had the maximum microhardness, 707.5 HV0.2, because the MCX (M = Cr, Nb, Mo)-reinforced phase appeared on the upper part of the coating. The wear rates were 3.65 × 10−5, 2.97 × 10−5, and 6.98 × 10−5 mm3·n−1·m−1. The wear mechanism of the three coatings was abrasive wear and adhesive wear. When the laser power was 1600 W, the coating had the minimum wear rate, which exhibited the best wear resistance. When the laser power was 1600 W, the upper part of the coating to the bonding zone was mainly composed of equiaxed crystals, dendrites, cellular crystals, columnar crystals, and planar crystals. The fine crystals and compounds caused a decrease in wear volume, and they had the most optimal wear resistance.

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Direct laser patterning of ruthenium below the optical diffraction limit

Cruciani,

Vreugdenhil,

van Vliet

et al. 2024

Applied Physics Letters

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We describe a method that can be used to produce ruthenium/ruthenium oxide patterns starting from a ruthenium thin film. The method is based on highly localized oxidation of a small surface area of a ruthenium film by means of exposure to a pulsed laser under ambient conditions. Laser exposure is followed by dissolution of the un-exposed ruthenium in a NaClO solution, which leaves the conductive, partially oxidized ruthenium area on the substrate. Spatially selective oxidation, material removal, and, by implication, patterning, are, therefore, achieved without the need for a photoresist layer. Varying the exposure laser parameters, such as fluence, focus diameter, and repetition rate, allows us to optimize the process. In particular, it enables us to obtain circular Ru/RuO2 islands with a sub-diffraction-limited diameter of about 500 nm, for laser exposure times as short as 50 ms. The capability to obtain such small islands suggests that heat-diffusion is not a limiting factor to pattern Ru by laser heating on a (sub-)micron scale. In fact, heat diffusion helps in that it limits the area where a sufficiently high temperature is reached and maintained for a sufficiently long time for oxidation to occur. Our method provides an easy way to produce metallic Ru/RuO2 (sub-)micron structures and has possible applications in semiconductor manufacturing.

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Laser-induced electron dynamics and surface modification in ruthenium thin films

Cited by 7 publications

References 43 publications

Femtosecond Laser-Induced Emission of Coherent Terahertz Pulses from Ruthenium Thin Films

Femtosecond Laser-Induced Emission of Coherent Terahertz Pulses from Ruthenium Thin Films

Microstructure and Properties of Inconel 718 Coatings with Different Laser Powers on the Surface of 316L Stainless Steel Substrate

Direct laser patterning of ruthenium below the optical diffraction limit

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